I slept on it and figured out what is wrong with this teacher's approach. Bear with me.
Often in learning, we use
mnemonics as a short cut. An example would be "Every Good Boy Deserves Fudge" to learn the G clef. The whole point of a mnemonic is that it needs to be easier to remember than what you're trying to learn.
I think what happened in this case is that the teacher knows the modes quite well. So the teacher is using his prior knowledge of modes as a mnemonic to play the major scale in different fingerings starting from any note, because that is the easiest way for the
teacher to conceptualize it.
The problem is that, if the student doesn't already have the modes well-memorized, or doesn't often play in modal genres, then the mnemonic is useless to that student because it is more complicated than the actual concept the student was trying to trying to learn in the first place!
An analogy would be if I said "it's easy to learn to count to ten: all you need to do is remember the first ten letters of the alphabet, and that A=1, B=2, etc." Why not just learn the numerals 1-10 and leave the alphabet out of the discussion?
It is easier just to say "Here's a fingering starting from the 1st degree of the major scale. Here's a fingering starting from the 2nd degree. Here's a fingering from the 3rd degree." And so on. The only mnemonics necessary in this case are to know the numbers from 1-7 and the construction of the major scale.
It's also worth mentioning that musicians already have a common vocabulary word for "playing in different regions of the neck." It is called
position and is usually defined as "the fret at which you place your 1st finger." So instead of saying "I am playing G Major in the Locrian Position" you could say "I am playing G Major in 2nd position." This is standard terminology and will allow you to communicate your ideas to a wider group of musicians than your teacher's non-standard mnemonic.
